The RSPCA warns trafficked puppies may be suffering from illnesses
A campaign to alert people to the "despicable" practice of "puppy trafficking" is being launched by animal welfare charity the RSPCA.
Traffickers mainly trade pedigree dogs and often use the internet, newspaper adverts and even pet shops, it warns.
Trafficked dogs could be sick or dying or have behavioural problems, it says.
It advises dog buyers to try to see a puppy with its mother in the place it was bred and to be particularly wary if the breeder is from outside the UK.
Its campaign will feature leaflets for members of the public and information on the organisation's website.
As part of the campaign, undercover RSPCA officers bought six puppies - two of which turned out to have potentially fatal illnesses.
The charity said government-funded advice service Consumer Direct had more than 700 calls relating to puppies last year.
Many of these were about animals that became ill soon after they were purchased or were not as described in adverts.
RSPCA chief veterinary adviser Mark Evans said: "Puppy trafficking is a despicable, profit-driven business. We want the dog-loving public to destroy the puppy trafficker's market.
"If you're planning to buy a puppy, do your homework. Question everything and make absolutely sure the puppy you buy has come from a loving, caring home.
"Let common sense prevail and if something doesn't seem right, it probably isn't, so walk away."
The RSPCA advises buyers:
- Always try to see a puppy with its mother in the place where it was bred, and pay attention to the mother's size, health, personality and reaction to the puppy - is it the real mother?
- Try to see the father too
- Try to find out as much as possible about where the puppy has come from, and beware if the breeder is from outside the UK
- If you are told the puppy has been vaccinated, check the vaccination cards carefully
- Be wary if the vet's contact details are not visible, or have an address outside the UK
- Never buy from someone who offers to deliver your puppy or arranges to meet you somewhere
- Never buy a puppy just because you feel sorry for it
Caroline Kisko, spokeswoman for the Kennel Club, said it welcomed the campaign.
"If every puppy buyer bought from a breeder and saw the puppy at its home this practice of puppy trafficking would stop overnight," she said.